This report produces the last 3 times each song has been played and how many shows it had been between each time it was performed. So

Energy (8/4/13 - 226, 7/21/13 - 8, 7/17/13 - 3 ave 79.0)

means that Energy was last played on 8/4/13 which was 226 shows ago. Before that it was played on 7/21/13 which was 8 shows prior. Before that it was played on 7/17/13 which was 3 shows prior. The average of 3, 8, and 226 is 79. The score at the end is the average of all of those averages.

If you're wondering, the example is from 7/9/19, the show that finally inspired me to add an explanation to help people out.